Pipe-bending mandrel



Jan. 3, 192s.A

" P. MUELLER ET AL PIRE BENDING MANREL Elummgs Patented J an. 3, 1928- UNITED STATES PATENTE-OFFICE.,

PHILIP IMU'EIJLEB.,l 0F DECATUR, AND ANTON C. SCHUERMANN, IDIEGEASED,v LATE lB' DEGATUB, ILLINOIS,- BY HELENA SCHUERMANN,

nxnourmx, or DEGATU'B., ILLI- NOIS, ASSIGNORS TO .ADOLPE MUELLEB, TRUSTEE, 0F DECA'UR, ILLINOIS. K

rijen-Bariatric mmm..

Application tiled4 October 17, 1925. .Serial No. 63,188.

The present inventionrelates to improvements in mandrels employed for .bending tubes or pipes, and particularly to thattype of mandrel which includes a flexible sectionadapted to be inserted in a tube andf'bent therewith about a suitable axis.

The particular' object of the invention is to provide a mandrel of the type or character referred to in which there will be provided a continuously smooth surface that will contact'with the inner face of the tube wall during the bending operation. With this end in view, the improvedmandrel includes a plurality of superposed thin, strips of resilient material providing an exterior y smooth surface throughout substantially the entire length of the flexible mandrel section, which surface will contact with the inner face of the tube wall and prevent distortion of such wall during the bending operation.

In the y.accompanying drawings:

Fig. 1 is an elevation of one embodiment of the invention, the supporting stemor rod and an adjustable sleeve being shown in section. Y Y

Fig 2 2 of Fig.v 1. f

Fig. 3 is an elevation, partly in of a slightly modified form.

' Fig., 4 is a transverse Vsection on the 'line 4-4=ofFig.3.`

Fig. 5 is a transverse form. l

Referring particularly to Figs. 1 and 2, the improved mandrel comprises a rigid rod or'stem l Awhich is provided, at one end, with a suitable socket in whichf are secured a series Yof superposedelongated resilient metal- 'strips 3. The strips 3 are of such form that, collectivelyg-tlhey provide Ka body of circular section,

'section of another mandrel or inclined. l Y

uBy employinga mandrel of the character shown in Figs. 1-and` 2, it is possible to bend 'a tube 'without' causmgany" distortion Aof the wall thereon-,and thereby avoid 'the 2 is a transverse section 011 the line .necessity for employing, at the free end of the mandrel, a sizing head, such as is commonly required to restore the desired cross sectional form of the tube as the mandrel is withdrawn' after the bendino' operation.

As repeated bendings ofthe exible body may tend to cause the several resilient'vstrips to separate slightly, it is preferredto surround such str1 s with a sleeve 4.A This' sleeve embraces t e series of stripsA suiiicient` ly close toretain them in the desired cy1indrical form, andl is adapted to be manually reciprocated over said strips to restore them to the original,l desired, position in case any such separation, as is above referred to, may have taken place. The length of the sleeve is, ofcourse, relativelyslight, and it is positioned adjacent-'the rod or stem 1 when the flexible section of thev mandrel is inserted in a tube. i'

p Instead of formin the vilexlible section solely from thin resi ient strips, as shown in Figs. 1 and 2, it is possible to obtain' the advantages of having a continuously smooth surface for contact with the interior ofy the tube to be bent by ,providing .two series of such stri s at diametricallyo p0- site points of a suitable flexiblecore. glich an arrangement is .illustrated in Figs. 3, 4-

and 5.

Referring tO/Fig. e, the ma or' stem 1 0f fthe-f mandrel .is connected to one end of a flexible body which comprises a series of pivotally connected core members ,5. lwhich are surrounded by andy pivotallyconnected with sections y6 of the cross sectional form shown in Figs. 4 and 5. Y' As shown, Aeach tubular member 6 has oppositely arranged circular portions which are connected bydiametrically opposite fiat surfaces 7 ,A 8, and against each of such flat surfaces is arranged a plurality of thin resilient metal -strips `9` .which ,extend into'A suitable' -recesses in the stemor rod- 1, and Aare rigidly secured thereto. .k The several core sections 5 are interengaged by suit-able tongues and recesses, and

also pivotally connected by, transverse pivot'y pins 10. The-tubular body members Gare y in turn pivotally connectedby pivots 11 4 f sai the -core members, and 1n elevation,

members 6 aregiven s'uch a form as permits that the' mandrel may relative lateral movement `between them, so readily bend with the tube' surroundin it.

-The thil resihent stri s 9 are of diie'rentt lengths, as in the embo 'ment of the invention illustrated in Figul, andl said strips are not rigidly connected withth'e otherparts of the mandrel, except by the Screws :12, so

that they are capable of relative longitudinalmovement during the bending operation., j

At the terminall end vof the core, there is arranged asizinghead 14 which, a.s, usua1,

will have the 'A cross-'sectional form and be of thel samedime ions. as the bore` of. the tube to be vbent'. Hl'he number 'of ,strips-9 may be such as Vto make'the ilexible'se'ction of the mandrel circular in cross section sub- ^stantially throughout its' length, as shown the amount of-fricton between themaudrel inv Fig. 5, or, preferred, the number of such 'strips'in one 44of the groups may be4 slightly less'than' .that in the other, so that there will ,be provided a substantiallyatf surface 15 throughouttlre len h. ofthe flexi; 'ble section which will allow ight collapslng of the wall of the tube .being .bent and reduce and tube during .the bending operation- As the mandrelis withdrawnfrom-the bent tube, the head 14 willact to restore' to the' desired l circular, crossl sectional,..for1 n any portion o'f the tube which may have col-l lapsed against the surface 15. It is preferred to employ a sleeve 4 which can be'reciproycated over 4thel flexible'v section of the mandrel in the formA of .the invention show n in Fig. 3, as well as that shown in Fig. 1, said sleeve acting, asbefore described, to radially compress the resilient 'stri'ps'and" maintain tended to e limited to the -ex'act details shown. f y 1 .j Having thus described' the' invention, what gitudina lg them in close contact, in case, 'after 'repeated operations, .t 'ere is a tendency 'for them to separateor become radially -spaced at the free ends.

It is" believed 'tha't themethod of using.

and advantages of the construction -hereinbeforedescribed will be readily apparent from the description andthe-drawings, and it is to be understood, of course, ,that,'ex cept where' specilically set forthyin thel aceompanyin 'claims,the .invention is notina-ex'ible body including a series-of su `roundin the ilexiblebody thereof..n I

a series of super'-V cuied adjacent1 one end, the strips being'of diierentlengths and arrangedso that the free endsthereof extend'successively greater fdistances 'from the stem.

3, A tubel bendinA mandrel -comprising a flexible body` inclu ing'a' series of lsuperposed, thin, strips of .resilient material, a

.stem to which .all of said strips are secured Iadjacent one end,"said strips being .of different lengths andarranged so that the free ends thereof `extend successively greater distances from :the stem, and a' sleeve closely 'surrounding the flexible body` and'vmovable longitudinally' thereof.

"4. A vtube bending mandrel comprising- 'a core formed' .by a plurality of pivotally ccnnecltied' members a stem, and a t in strip o resi the-core to formA a smooth" unbroken surface over the of the core.

t materia connected at one end to y the' stem and extending longitudinally of ljoints between the members v 5, A 'tube bending' mandrel com risiilg -v a' core formed by a plurality of ivota ly con- .nectedmembers, a stem, and t strips of resilient material connected at one end to the stem land 'extending longitudinally of the core .to provide two diametricall opposite,(smooth surfaces over the joints tween the members ofthe core.

6. Al tubebending mandrel compr'ving a .core formed'of. a pluralityA of pivotally con nected meinbers,` a; stem, and two sets `of thin strips of resilient material attached to the stem and..extending across joints between the members of the core at diametri#v cally opposite points, .each said set includmg a plurality of perposed strips. tube. bending mandrel comprising a core lformed lof'a -.plurality of pivotally connected. members,"each .being of substane ',tially circular form in cross section .with i y diametncally opposite, parallel' truncated surfa "a".stem and la lurality of superposedbjn strips of resdlient material at- .y .tached to the stem aton -eiidandfextending over the-truncated portie l of 4the core' memrs and across thejointsbetween saidimemrs. I A l I y i I 8. tubo bending mandrel comprising a ','oorelformed of a' plurality of pivotally connectedmembers, a stem .attachedto oneend o;-f".t`l 1'e'licore, a head connected to Itlieother' .elidof the .c ore, 4and a .plur'alityfof stripsjof resilient materialsecured atfone end tothe. stem 'and extending. therefrom overjthe core, to'fo'rmsmooth surfaces across .'ltilidts between thelcore members,"to ward theU A nec'ted'members, a stem attached to one end I .of -thecore, 'a'.head connected to themther".

'end .of'thecore,;a plurality :of thin-strips off'l materialsecured' 'at one. Iend to the 'A t.\1be;bending` 'mandel 'comprising a bending rnandrelfconi` a' iiexible body, substantially ieylin rical in".

" ncrosssection and includ' t posed, thin, stri s of res' ent material, `and a, stem to whi all ofjsaid strips arese 13eme? to formsmooth surfaces across joints between the'core members, toward the head,

and a sleeve embracing said strips and core and movable longitudinally thereof.

, 10. A tube bendin mandrel comprising a flexible body inclu ing a series of superimposed thin stri s 'of resilient material connected together adjacent one end, and means adjustable longitudinally of the -mandrel for exertin pressure on said strips of resilient materia to maintain contact between disconnected portions of Such strips, for the Vose described.

' 11. A tube bending vmandrel comprising a .exible body including. a series of superimposed, thin, strips of material connected` I together at one end and a sleeve closely surroundin vsaid and" movable longitudinally-t ereof, sai sleeve being normal- 1y sitloned near the connected ends of the resilient strips.

In testimony Iwhereof, we, PHLIP M'UEL- LER, and HELENA SCHUERMANN, executrix of the last will and testament of ANTON C. NN,' deceased, have hereunto set our hands.

PHILIP MUELLER. y' HELENA SCHUERMANN, ecutrw of Anton 0. Schaam/rm, De- 

